Project 3: A Trial of TTP488 to Slow the Rate of Clinical Progression of Patients with AD Currently FDA-approved drugs for Alzheimer's disease (AD) are primarily symptomatic and do not target pathogenic pathways. Deposition of amyloid beta protein (Ali) in plaques and inflammation may offer therapeutic targets. The receptor for advanced glycation endproducts (RAGE) is expressed in neurons and astrocytes and is upregulated in AD. RAGE interacts with multiple ligands, including AIJ, and may link AS to inflammation and neuronal dysfunction. Inhibition of RAGE/ligand interactions may slow the progression of neuropathological defects and cognitive changes induced by AH. TTP488 is a small molecule identified by a screening process, that binds to RAGE in vitro, and inhibits the interaction of RAGE with its ligands. In vivo, TTP488 crosses the blood brain barrier and, in transgenic mouse AD models, reduces brain amyloid load and behavioral dysfunction. The compound is well tolerated in healthy human subjects, including daily oral dosing for 1 month in elderly subjects, and longer safety studies in patients with AD are ongoing (data available in February 2006). We propose to carry out a randomized, double blind, multicenter trial in 350 patients with mild to moderate AD treated with one dose of TTP488 or placebo for 18 months. Subjects will be randomized 60:40 to receive active drug or placebo. The hypothesis is that treatment with TTP488, relative to placebo, will lead to slower clinical decline. Subjects will be followed at regular intervals to assess cognition, function, behavior, safety and tolerability. Primary outcome measures are the ADAS-cog and CDR Sum of Boxes (CDR-SOB). Secondary outcome measures are the ADCS-ADL and Neuropsychiatric Inventory (NPI). Drug levels and biomarkers will be measured in plasma. Standard therapy for AD will be permitted. The study has 90% power to detect a 41% or larger change on the ADAS-cog assuming a 3.8 point mean annual change in the placebo group, and has 80% power to detect a 35% change.